Security advisory

{
  "id": "59eebde74947588296446b42940cc8fdf48690f435e782df4607ff5b511cb72b",
  "url": "https://osv.dev/vulnerability/CVE-2021-20234",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-20234",
    "summary": "An uncontrolled resource consumption (memory leak) flaw was found in the ZeroMQ client in versions before 4.3.3 in src/pipe.cpp. This issue causes a client that connects to multiple malicious or compromised servers to crash. The highest threat from this vulnerability is to system availability.",
    "evidence": "osv:CVE-2021-20234",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-20234",
      "aliases": [
        "CVE-2021-20234",
        "GHSA-wfr2-29gj-5w87"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/zeromq/libzmq",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "04f5bbedee58c538934374dc45182d8fc5926fa3"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:zeromq:libzmq:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.3.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.3.2",
            "v4.3.1",
            "v4.3.0",
            "v4.2.5",
            "v4.2.4",
            "v4.2.3",
            "v4.2.2",
            "v4.2.1",
            "v4.2.0",
            "v4.2.0-rc1",
            "v3.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-20234.json"
          }
        }
      ],
      "modified": "2026-10-24T10:50:11.091892772Z",
      "provider": "osv",
      "references": [
        "https://bugzilla.redhat.com/show_bug.cgi?id=1921972",
        "https://github.com/zeromq/libzmq/security/advisories/GHSA-wfr2-29gj-5w87"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:a:zeromq:libzmq:*:*:*:*:*:*:*:*"
            ],
            "vendor_product": "zeromq:libzmq",
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "4.3.3"
                  },
                  {
                    "fixed": "4.3.3"
                  }
                ],
                "source": "CPE_RANGE"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-20234",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 442031,
  "published_at": "2021-04-01T14:15:13.123+00:00"
}